/*
 * %W% %E%
 *
 * Copyright (c) 2006, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.sound.sampled;

import java.io.InputStream;
import java.io.PushbackInputStream;
import java.io.IOException;


/**
 * An audio input stream is an input stream with a specified audio format and
 * length.  The length is expressed in sample frames, not bytes.
 * Several methods are provided for reading a certain number of bytes from
 * the stream, or an unspecified number of bytes.
 * The audio input stream keeps track  of the last byte that was read.
 * You can skip over an arbitrary number of bytes to get to a later position
 * for reading. An audio input stream may support marks.  When you set a mark,
 * the current position is remembered so that you can return to it later.
 * <p>
 * The <code>AudioSystem</code> class includes many methods that manipulate
 * <code>AudioInputStream</code> objects.
 * For example, the methods let you:
 * <ul>
 * <li> obtain an
 * audio input stream from an external audio file, stream, or URL
 * <li> write an external file from an audio input stream
 * <li> convert an audio input stream to a different audio format
 * </ul>
 *
 * @author David Rivas
 * @author Kara Kytle
 * @author Florian Bomers
 * @version %I%, %E%
 *
 * @see AudioSystem
 * @see Clip#open(AudioInputStream) Clip.open(AudioInputStream)
 * @since 1.3
 */
public class AudioInputStream extends InputStream {

    /**
     * The <code>InputStream</code> from which this <code>AudioInputStream</code>
     * object was constructed.
     */
    private InputStream stream;

    /**
     * The format of the audio data contained in the stream.
     */
    protected AudioFormat format;

    /**
     * This stream's length, in sample frames.
     */
    protected long frameLength;

    /**
     * The size of each frame, in bytes.
     */
    protected int frameSize;

    /**
     * The current position in this stream, in sample frames (zero-based).
     */
    protected long framePos;

    /**
     * The position where a mark was set.
     */
    private long markpos;
    
    /**
     * When the underlying stream could only return
     * a non-integral number of frames, store
     * the remainder in a temporary buffer
     */
    private byte[] pushBackBuffer = null;
    
    /**
     * number of valid bytes in the pushBackBuffer
     */
    private int pushBackLen = 0;
    
    /**
     * MarkBuffer at mark position
     */
    private byte[] markPushBackBuffer = null;
    
    /**
     * number of valid bytes in the markPushBackBuffer
     */
    private int markPushBackLen = 0;
    

    /**
     * Constructs an audio input stream that has the requested format and length in sample frames,
     * using audio data from the specified input stream.
     * @param stream the stream on which this <code>AudioInputStream</code>
     * object is based
     * @param format the format of this stream's audio data
     * @param length the length in sample frames of the data in this stream
     */
    public AudioInputStream(InputStream stream, AudioFormat format, long length) {

	super();

	this.format = format;
	this.frameLength = length;
	this.frameSize = format.getFrameSize();

	// any frameSize that is not well-defined will
	// cause that this stream will be read in bytes
	if( this.frameSize == AudioSystem.NOT_SPECIFIED || frameSize <= 0) {
	    this.frameSize = 1;
	}

	this.stream = stream;
	framePos = 0;
	markpos = 0;
    }


    /**
     * Constructs an audio input stream that reads its data from the target
     * data line indicated.  The format of the stream is the same as that of
     * the target data line, and the length is AudioSystem#NOT_SPECIFIED.
     * @param line the target data line from which this stream obtains its data.
     * @see AudioSystem#NOT_SPECIFIED
     */
    public AudioInputStream(TargetDataLine line) {

	TargetDataLineInputStream tstream = new TargetDataLineInputStream(line);
	format = line.getFormat();
	frameLength = AudioSystem.NOT_SPECIFIED;
	frameSize = format.getFrameSize();

	if( frameSize == AudioSystem.NOT_SPECIFIED || frameSize <= 0) {
	    frameSize = 1;
	}
	this.stream = tstream;
	framePos = 0;
	markpos = 0;
    }


    /**
     * Obtains the audio format of the sound data in this audio input stream.
     * @return an audio format object describing this stream's format
     */
    public AudioFormat getFormat() {
	return format;
    }


    /**
     * Obtains the length of the stream, expressed in sample frames rather than bytes.
     * @return the length in sample frames
     */
    public long getFrameLength() {
	return frameLength;
    }


    /**
     * Reads the next byte of data from the audio input stream.  The audio input
     * stream's frame size must be one byte, or an <code>IOException</code>
     * will be thrown.
     *
     * @return the next byte of data, or -1 if the end of the stream is reached
     * @throws IOException if an input or output error occurs
     * @see #read(byte[], int, int)
     * @see #read(byte[])
     * @see #available
     * <p>
     */
    public int read() throws IOException {
	if( frameSize != 1 ) {
	    throw new IOException("cannot read a single byte if frame size > 1");
	}

	byte[] data = new byte[1];
	int temp = read(data);
	if (temp <= 0) {
	    // we have a weird situation if read(byte[]) returns 0!
	    return -1;
	}
    	return data[0] & 0xFF;
    }


    /**
     * Reads some number of bytes from the audio input stream and stores them into
     * the buffer array <code>b</code>. The number of bytes actually read is
     * returned as an integer. This method blocks until input data is
     * available, the end of the stream is detected, or an exception is thrown.
     * <p>This method will always read an integral number of frames.
     * If the length of the array is not an integral number
     * of frames, a maximum of <code>b.length - (b.length % frameSize)
     * </code> bytes will be read.
     *
     * @param b the buffer into which the data is read
     * @return the total number of bytes read into the buffer, or -1 if there
     * is no more data because the end of the stream has been reached
     * @throws IOException if an input or output error occurs
     * @see #read(byte[], int, int)
     * @see #read()
     * @see #available
     */
    public int read(byte[] b) throws IOException {
	return read(b,0,b.length);
    }


    /**
     * Reads up to a specified maximum number of bytes of data from the audio
     * stream, putting them into the given byte array.
     * <p>This method will always read an integral number of frames.
     * If <code>len</code> does not specify an integral number
     * of frames, a maximum of <code>len - (len % frameSize)
     * </code> bytes will be read.
     *
     * @param b the buffer into which the data is read
     * @param off the offset, from the beginning of array <code>b</code>, at which
     * the data will be written
     * @param len the maximum number of bytes to read
     * @return the total number of bytes read into the buffer, or -1 if there
     * is no more data because the end of the stream has been reached
     * @throws IOException if an input or output error occurs
     * @see #read(byte[])
     * @see #read()
     * @see #skip
     * @see #available
     */
    public int read(byte[] b, int off, int len) throws IOException {

	// make sure we don't read fractions of a frame.
	if( (len%frameSize) != 0 ) {
	    len -= (len%frameSize);
	    if (len == 0) {
	    	return 0;
	    }
	}

	if( frameLength != AudioSystem.NOT_SPECIFIED ) {
	    if( framePos >= frameLength ) {
		return -1;
	    } else {

		// don't try to read beyond our own set length in frames
		if( (len/frameSize) > (frameLength-framePos) ) {
		    len = (int) (frameLength-framePos) * frameSize;
		}
	    }
	}
	
	int bytesRead = 0;
	int thisOff = off;
	
	// if we've bytes left from last call to read(),
	// use them first
	if (pushBackLen > 0 && len >= pushBackLen) {
	    System.arraycopy(pushBackBuffer, 0,
	                     b, off, pushBackLen);
	    thisOff += pushBackLen;
	    len -= pushBackLen;
	    bytesRead += pushBackLen;
	    pushBackLen = 0;
	}
	
	int thisBytesRead = stream.read(b, thisOff, len);
	if (thisBytesRead == -1) {
	    return -1;
	}
	if (thisBytesRead > 0) {
	    bytesRead += thisBytesRead;
	}
	if (bytesRead > 0) {
	    pushBackLen = bytesRead % frameSize;
	    if (pushBackLen > 0) {
		// copy everything we got from the beginning of the frame
		// to our pushback buffer
		if (pushBackBuffer == null) {
		    pushBackBuffer = new byte[frameSize];
		}
		System.arraycopy(b, off + bytesRead - pushBackLen, 
		                 pushBackBuffer, 0, pushBackLen);
		bytesRead -= pushBackLen;
	    }
	    // make sure to update our framePos
	    framePos += bytesRead/frameSize;
	}
	return bytesRead;
    }


    /**
     * Skips over and discards a specified number of bytes from this
     * audio input stream.
     * @param n the requested number of bytes to be skipped
     * @return the actual number of bytes skipped
     * @throws IOException if an input or output error occurs
     * @see #read
     * @see #available
     */
    public long skip(long n) throws IOException {

	// make sure not to skip fractional frames
	if( (n%frameSize) != 0 ) {
	    n -= (n%frameSize);
	}

	if( frameLength != AudioSystem.NOT_SPECIFIED ) {
	    // don't skip more than our set length in frames.
	    if( (n/frameSize) > (frameLength-framePos) ) {
		n = (frameLength-framePos) * frameSize;
	    }
	}
	long temp = stream.skip(n);

	// if no error, update our position.
	if( temp%frameSize != 0 ) {

	    // Throw an IOException if we've skipped a fractional number of frames
	    throw new IOException("Could not skip an integer number of frames.");
	}
	if( temp >= 0 ) {
	    framePos += temp/frameSize;
	}
	return temp;

    }


    /**
     * Returns the maximum number of bytes that can be read (or skipped over) from this
     * audio input stream without blocking.  This limit applies only to the next invocation of
     * a <code>read</code> or <code>skip</code> method for this audio input stream; the limit
     * can vary each time these methods are invoked.
     * Depending on the underlying stream,an IOException may be thrown if this
     * stream is closed.
     * @return the number of bytes that can be read from this audio input stream without blocking
     * @throws IOException if an input or output error occurs
     * @see #read(byte[], int, int)
     * @see #read(byte[])
     * @see #read()
     * @see #skip
     */
    public int available() throws IOException {

	int temp = stream.available();

	// don't return greater than our set length in frames
	if( (frameLength != AudioSystem.NOT_SPECIFIED) && ( (temp/frameSize) > (frameLength-framePos)) ) {
	    return (int) (frameLength-framePos) * frameSize;
	} else {
	    return temp;
	}
    }


    /**
     * Closes this audio input stream and releases any system resources associated
     * with the stream.
     * @throws IOException if an input or output error occurs
     */
    public void close() throws IOException {
	stream.close();
    }


    /**
     * Marks the current position in this audio input stream.
     * @param readlimit the maximum number of bytes that can be read before
     * the mark position becomes invalid.
     * @see #reset
     * @see #markSupported
     */

    public void mark(int readlimit) {

	stream.mark(readlimit);
	if (markSupported()) {
	    markpos = framePos;
	    // remember the pushback buffer
	    markPushBackLen = pushBackLen;
	    if (markPushBackLen > 0) {
		if (markPushBackBuffer == null) {
		    markPushBackBuffer = new byte[frameSize];
		}
		System.arraycopy(pushBackBuffer, 0, markPushBackBuffer, 0, markPushBackLen);
	    }
	}
    }


    /**
     * Repositions this audio input stream to the position it had at the time its
     * <code>mark</code> method was last invoked.
     * @throws IOException if an input or output error occurs.
     * @see #mark
     * @see #markSupported
     */
    public void reset() throws IOException {

	stream.reset();
	framePos = markpos;
	// re-create the pushback buffer
	pushBackLen = markPushBackLen;
	if (pushBackLen > 0) {
	    if (pushBackBuffer == null) {
		pushBackBuffer = new byte[frameSize - 1];
	    }
	    System.arraycopy(markPushBackBuffer, 0, pushBackBuffer, 0, pushBackLen);
	}
    }


    /**
     * Tests whether this audio input stream supports the <code>mark</code> and
     * <code>reset</code> methods.
     * @return <code>true</code> if this stream supports the <code>mark</code>
     * and <code>reset</code> methods; <code>false</code> otherwise
     * @see #mark
     * @see #reset
     */
    public boolean markSupported() {

	return stream.markSupported();
    }


    /**
     * Private inner class that makes a TargetDataLine look like an InputStream.
     */
    private class TargetDataLineInputStream extends InputStream {

	/**
	 * The TargetDataLine on which this TargetDataLineInputStream is based.
	 */
	TargetDataLine line;


	TargetDataLineInputStream(TargetDataLine line) {
	    super();
	    this.line = line;
	}


	public int available() throws IOException {
	    return line.available();
	}

	//$$fb 2001-07-16: added this method to correctly close the underlying TargetDataLine.
	// fixes bug 4479984
	public void close() throws IOException {
	    // the line needs to be flushed and stopped to avoid a dead lock...
	    // Probably related to bugs 4417527, 4334868, 4383457
	    if (line.isActive()) {
		line.flush();
		line.stop();
	    }
	    line.close();
	}

	public int read() throws IOException {
	    
	    byte[] b = new byte[1];
	    
	    int value = read(b, 0, 1);
	    
	    if (value == -1) {
		return -1;
	    }
	    
	    value = (int)b[0];
	    
	    if (line.getFormat().getEncoding().equals(AudioFormat.Encoding.PCM_SIGNED)) {
		value += 128;
	    }

	    return value;
	}


	public int read(byte[] b, int off, int len) throws IOException {
	    try {
		return line.read(b, off, len);
	    } catch (IllegalArgumentException e) {
		throw new IOException(e.getMessage());
	    }
	}
    }
}
